Selective signaling system



Nov. 25, 1952 VROQM SELECTIVE SIGNALINGSYSTEM 2 SHEETS-SHEET 1 FiledAug. 15, 1950 IN [/6 N TOR E. moo/4 ATTORNEY 2 SHEETS-SHEET 2 Nov. 25,1952 E. vRooM SELECTIVE SIGNALING SYSTEM Filed Aug. 15, 1950 PatentedNov. 25, 1952 PATENT ()sEFldiEi.

SELECTIVE SIGNALING SYSTEMT Edwardifva'o'om, Ossiixing, Nu Y2," assignorto aBelll Telephone"; liaboratories Incorporated New? Yorke-NeY a-corporation of New York Application Aug stfi, 1950; Serial No. 179M15-ioiolaimss (01. 117-353)- 15. Thisiiiinvention:relates to:a-se1e'ctiveesignalinge system :andJmorei particularlm to apparatus op'erable only inresponse to the --rec.eipt of a-repre-. sent'ation:ofjthe: designation of that"aapparatiisa- An object-sot this: invention:is. the rapid and accurate *iascertainment; of ..'the arece'ipt' ofaselected: one" ofz'a! plurality;- of: designations;

The: invention 1' may: 'find iapplicatiom inmany=- fildSiOf.communicationrsuch as :in t'elephone' ors' telegraph;,switch'ingiisystems; mobile n radio sys} temsgz shipr-to shoreco'mrmmication systemsy train. disp''atchingtlsystems, etc; Siichsystems normally comprisesaz pli'irality: of terminatin'g or called:stations each-50f; which is suitably {deseignatedjbyaanumbenxatseries of.letterspor a'comhinationyof; numbers'x and letters;- In: order toestablish: a: communication path '5 to a particular: oneiof: such:called; stations,v it is anormally 'neces sary for the called party tobe informed audiblyand/or 'visuallyethat he islbeing called. Howeven:int-many :systems; the signals representin gaalargeigroupoiliiesignations-are received 'bycach ofiithes: stations. Consequently,it. is desirablethat means bezprovidedto alertlthe-called party onlywhen his particular: designation is received? Therefore; inrgeneraLf;thisl'inventioncomprises aysystemsoperahle in response tog-the receipt'ofag preselectedmneeonly ofzra" pluralit ylsof composite: signals to--energize a visual; oniaudibl'e signali aefeaturexson the. inventionisxthejeutilizatiom of cold} cathode gaseouszdischarge; steppingde'vices each; having gar plurality :ofzcathodes. Y

Anothen: feature jofzithis'iinvention'. i's'"the provisionlofone:multicathodeigaseous dischargetic vicedforeach z'digit orrelementsofiiithezsubscribers 351 designationsn, I 1 Another feature ofthiss'invention is: a means: for: successively operating,thezmulticathode gaseousdischarge-devicesi only if eachxof the-succes=- A siveldigits or elements: received correspond with" the;elementon digit. at: thatiipoint in? the se*-- quence in; thedesignation; of; the: station; with w'hiizhthe {apparatus is associated;

' Theprinciplesof the inyentionrm'ay -be: more fiillij understood fromthe-Efollowing jdetailed-.,lfiea 4:5a scriptiong of I a? preierredembodiments. thereof when", read- "with, retrence to;.thdtacdompanizing: drawings, in. which: v

efl ista elevatiqnal view ofaaz-multicathodez glowdischarge;device-illizstratiyeebf: one :type M tuliensuitablefor; user-in the 1presents-system Fig. 21s asectional view taken-along;::2-"-L-2 of Eige.1 illustrating the arrangement oil the "sev eral "cathodes ,andfthecooperative .relationithere'e of with the anode, 1 a 7 portionofz'ftheranodesheingg 55'.

broken away to: show. certain; of; the. cathodes.

morei'clearly;;;andi:

Fig: 3 is la'rcircuit' "diagram representing; ai'pre-e' ferred;ambodiment' of the: invention:

The :multicathode'; stepping-"tubes. which are: employed: in the presentsystem may be ofz'anyxsuitable: type;. A, tubeiqoperableiin.agsuitableamanner isdisclosedQfor example; in United States: Patent 2,575,370granted November 20,.19'51; to]: M. A; Townsendathe disclosureofwhichfis incorporated-herein hyigreference.- A:' represent'a'f-i:tion-of;v thatv tubeis; presented as. Figs. 1 and: 2,:..'of;: thepresent disclosure.

In. general, the disclosed gaseous: discharge -de'- vice, comprises ananode "and a plurality: ofv cold; cathodes in cooperative'relationshipwith the-an ode; the cathodes -.being mounted inarow which mayIce-rectilinear,circular OIfOf' other geomete: ricalt form.The-cathodes; or certain of-"them; are electricallygrouped andare=soconstructedz and arranged that i the discharge between one.cathode and the anode may be stepped or shift edselectively to-- a :pathbetween the anode? and another cathode in response to signahpulses; thedischarge shifting or advancing one. position for; each pulse.

Referring now to 'Figs.-1 and'2 of the drawings the tube of theexemplary type comprises a nplu rality of cathodes; l l,- hereinafterreferred; :to as Ai cathodes, anda second plurality of cathodes:

' l2; hereinafterdesignated as B cathodes,:,alle

ofJthe-cathodes beingmounted in a .,circular;. ar5 rav; with each -A?cathode H interposedptwo; Bi cathodes-IL The main anode ii-h m andlisshown tobe ring-shaped,- and-is support-v1 edin spaced relation withthe=A= and 3B catha odes. An auxiliary, start, reset or normaliz nelectrode l4-is.-also provided In one" method of. operating-the steppingtube-,-: the start electrode 1 4' is employed as a start-anode;cooperating with the-electrode Y I 5 which2senves asz a start,- cathode,A a suitable positive potential is the start cathode l 5 .with;conductiorrthen itransferring' so as to exist betweenwthe; maimsanode l3and:thestartca-thode:I 5? If: anegative Zpul'sm then, be 'appliedl-tothe B'fl': catl'mai'es: l2; the-disk.- chargeiwwill;transientinitia'lly'r so v as-ito.- exist be tweentthes'mainianodezandthe rst'oneor-tne 13" in Fig. 2. At the cessation of the pulse, thedischarge will transfer so as to exist between the main anode and thefirst one of the A cathodes in a counter-clockwise direction in thestructure as shown in Fig. 2. This first A cathode is labeled I! in thestructure as shown in Fig. 2 and is supplied with a suitable voltagethrough an impedance. In a similar manner, successive pulses applied tothe E cathodes I2 will cause the conductive path in the tube to transferso as to exist between the main anode i3 and the successive A cathodesH. The directivity of the stepping is accomplished by the constructionof the cathodes, in a manner fully set forth in the above-cited patentapplication or in any other suitable manner.

As the conductive path progresses step by step from position to positionin the tube, the con duotion is limited to one path at a time, i. e.,the conduction between the main anode and the previous A cathode II isextinguished. This may be accomplished by utilizing asuitable impedancein series with the main anode of the device whereby the increasedvoltage drop across this impedance; resulting from the't'ransfer ofconduction to a B cathode I2, is sufiicient to cause the voltage betweenthe main anode I3 and an A cathode I I to fall below the sustainingvalue.

A circuit embodying the principles of the invention is shown in Fig. 3of the drawing. In this circuit a plurality of multicathode steppingtubes TI to T is provided. These tubes may be of the type shown in Figs.1 and 2, and in that event, in tube TI, main anode MAI is thecorrelative of anode I3 in Fig. 2, the first B cathode IBI is shown ascathode IS in Fig. 2, the B cathodes IB2 to IE0 are shown as thecathodes I2 in Fig. 2, the first A cathode IAI is shown as cathode I? inFig. 2, A cathodes IA2 to I A0 are the correlatives of cathodes II inFig. 2, the start anode ISA is shown as electrode :4 in Fig. 2, and thestart cathode ISO is shown as electrode I5 in Fig. 2. Tubes T2 to T0 areprovided with electrodes similarly designated to those of tube TI exceptfor the appropriate change inthe initial character in each designation.

As an exemplary embodiment of the invention, a portion of a mobile radiotelephony system has been shown in Fig. 3. At each of the subscribersstations, such as the one represented in Fig. 3, a radio receiver RE anda radio transmitter TR are provided. This apparatus may be of anysuitable type well known in the art, and is associated with a telephonehandset HS in the nor mal manner. It is assumed that receiver RE iscontinuously operative to receive all of a relatively large group ofsubscribers telephonicdesignations, which are transmitted from one ormore central point and to apply all of these incoming designations toconductor 30I which is connected to battery through the upper winding ofpulsing relay L. The receiver is further assumed to be operable inresponse to the receipt of any subscribers designation to connect groundto conductor 302, whereby this ground is extended through the No. 3contact of the switchhook SW to operate off-normal relay ON.

Let it be assumed that a signal has been received by receiver RE andthat receiver RE has operated to energize relay ON and to cause currentto flow through the upper Winding of relay L to operate relay L so thatits armature is contacting the Nos. 3 and 4 contacts thereof. As

the several series of pulses representing the several letters or digitsof the called partys designation are applied to conductor 30I throughreceiver RE, relay L will release at each pulse and reoperate at thetermination of each pulse in the normal manner.

Additional windings are shown on relay L for special purposes. The lowerwinding of relay L is a biasing winding which opposes the upper oroperating winding sufiiciently to force relay L to release when theoperating winding is deenergized. When relay L operates, the energizingcircuit for the lower winding of relay L is completed through resistor304, No. 3 contacts of relays L and ON and to negative battery. When,subsequently, the upper winding of relay L is deenergized, the currentin the lower winding of relay L is such as to assist the start of therelease of relay L. The middle winding of pulsing relay L functions asan aiding winding, assisting in both the operation and release of therelay. When relay L is operated capacitor 305 is charged over a pathfrom ground, middle winding of relay L, capacitor 305, through the No. 3contacts of relays L and ON and to negative bat tery. When relay L isreleased, the above-traced charging path is interrupted and capacitor305 discharges through the winding of relay SR to ground. The currentflow through the middle winding of relay L, as a result of thedischarging of capacitor 305, is in a direction to aid the release ofrelay L and to insure the closure of the back contacts of that relay.When relay L is again operated, the charging path for capacitor 305 isreestablished'and the current flowing through the middle winding ofrelay L as a result of the charging of that capacitor aids the operationof relay L there-by insuring a steady front contact closure.

Relay ON is arranged to operate prior to the operation of relay L. Thismay be accomplished by controlling the time at which the receiver REgrounds the leads 30l and 302 or by the characteristics of the relaysper se. Upon the operation of relay ON and prior to the time that relayL hasfirst operated, negative battery is connected through the No. 3contact of relay ON, No. I contact of unoperated relay L and to groundthrough resistor 301 and, in parallel therewith, to ground throughcapacitor 308 and the upper winding of the pulse generator transformer339. As a result of the surge of charging current for capacitor 308through the upper winding of transformer 309, transformer 309 transmitsa positive pulse through the back contact of unoperated relay SR,conductor 3!!! and to the start anodes ISA to OSA of all the steppingtubes TI to T0. Since the start cathodes ISC to 0S0 are all connected tonegative battery, which may supply, for example, a negative 50-voltpotential, through individual resistors, each of the tubes TI to T0 willundergo an initial discharge between its start anode and its startcathode/ Since the main anodes MAI to MAO of all of the tubes areconnected to positive battery which may supply, for example, a positive-volt potential, through individual resistors, via conductor 3I3, andthrough the No. 2 contact of relay ON, each of the tubes TI to T0 willimmediately undergo a transfer of discharge whereby conduction willexist between the main anode MAI to MAO and the start cathode ISC to080, respectively, of the tubes TI to T0, respectively. All the tubes TIto T0 are now prepared for stepping.

acreage;

.Upvonzzthe initial.. operatio.n of..relay. L, a .cire

01111531185 completed 1 from. negative. battery; No; 3.. contacts of.relays r ON and L, .Winding of relay SR and to ground whereby relay SRis. operated. Itz will..be noted that. this. operation. of; relaySRcannot; occur. until. relay. L..has closed its No.- 3; contact; wherebyample timewill have: been provided ifor. the transmission; of the.positives puls ;byitransformer 309 through the back :con-.

tact 4.0L relay .SR as l was :hereinbefore. described.

It::may'..:.also be. noted; that. relay: SR. is of the.slosvetosrelease; type .so that it. remains operated despite: the;several momentary interruptions of its; energizing circuitresulting fromthe pulsing ofrelay: L;

At thefirst release of. relay. Lin responseto the. first. pulse: of the.first: digit of 'the received designation, capacitor 308 will chargeovertheabove-traced. path.. A. positive. pulse. is. transmitted'byetransformer 309 in. response to. the chargin inthesame mannerasabove described, butcsince relay- SR. is now, operated, this pulsewill r. be. transmitted through the front contact of operated relay. SR,conductor 315, through effective. to createany change in the conditionOfith circuits at. this time. Atthe next operation; of relay L at theend of the first'pulseof: the first digit of the received designation,-

capacitor'308will discharge. through resistor 331- to ground whereby anegative pulse Will be transmitted by. the pulse generator transformer339'- over. theabove traced path to ground through resistor3-l6'whereby' a negative pulse will be applied. to all of the B cathodesIBI to IE3 of tube. Tl. Inresponse to this first negative pulse appliedto, the B cathodes of tube Tl; the.

conductive-path in that tube will be transferred so. as.t0 exist betweenthe main anode MAI and th'e first B cathode IBI thereof. As aresult-,due to the increased voltage drop across anode resistor 31?, thepotential at the mainanode MAI of tube TI will drop to a point where thepotential difierence between the main anode MAI and the start .cathode-ISC is below the sustaining value, and that discharge path will therebybe'extinguished. As the pulse attenu ates, the discharge in tube Tl willagain transfer-so. as to exist between the main anode MA! and thefirst Acathode IAI which is connected 'to negative battery through resistor3l8. Although the potential drop across the A cathode resistor 3| 8 maybe employed as an output signal indicative of'the registration of thedigit lfthis has not been done in the preferred embodiment oftheinvention inasmuch as the digit 1 is normally not employed as thefirst digit ofa subscriber's designation.

At the next momentary release andreoperatioI-rof relay Lin-response tothe second pulse of T thefirst digit of the received designation, theconductive path in tube T l is successively stepped to the next Bcathode IBZ'and then to the next A cathode 1A2, with the priorconductive path between themain anodeMAl and the A cathode IAI beingextinguished; The riseainpotential of cathode 1A2 due to the potentialdrop across resistor 323 appearsatout-- put terminal 32!.

As the; subsequent .firstdigit pulses are. re

ceived; relay L will: continue .to follow the pulses.

alternatively .1 to... charge andr ;discharge.=capacitors 308;: whereby.transformer. 3091 will 2. continue to z transmit negative pulses to theB cathodes= of tubeJIEl; 'Ihe-steppingxof tubeTtcont-inues in. the;aboverdescribed-manner,. with. the conductive'. paththereinxfinallyresting onv that: one of, the .AT. cathodes corresponding.w-ith'thenum ber. of pulses: received... Therefore,- the" outputterminaL. associated .Wlth' the-selected -A' oath ode. carries.aupotential considerably positive -rela'- tive to-thepotential which issupplied to the out Put terminals which: are: connected tothe nonconducting A cathode.

An .output conductor. 322 is. connected? to 'a SBIECIJBdLOl'lBlOf. theAfcathode output terminals; of. tube. .Tl This connection :is made inaccord"---' ance. withthe-firsti'digit oft-he designation of the.particular. subscribers station with-whichthe apparatusisassociated.Thus, assuming the first. digit'rof: the. designation tobe 8(or;.-acorresponding letter); output conductor -322-*-is connected. to:output: terminal: 323 i which/is connected .tothej eighth A cathode [A8of tube Tl, asshown'.

At: the termination of the pulses representing-5 any I one digit, relayRA is operated and remains' operated: during the interdigital delayperiod At any .timethatrelay Lis operated, capac tor 332. ischargingover a path from positive battery; No. 2. contact of relay ON, windingof relay'R-A; resistor. 333;: capacitor 332- and to ground: Asiaconsequence; a rising p-ositivespotential is applied to the start. anode33=4of"tube RAI. However; th-etime constant of-that circuitislonger-than? the time betweenhe-pulses representin-g any one digit of a.subscribers designation, and consc quently prior to. thetime'that adischarge is initiated intube RAl, relay-L willmoment-arlly release andcapacitor 332 will dischargeand; m fact, charge oppositelythroughresistor 335; No. 2 contact of released relay- L, No. 3 contact of relayON and to n-egativebattery. At the-end; of the pulses representing anyone digit; how--. ever, an inter-digital time will-elapse and "during;this-longer period capacitor 332 will rise-tea sufficient positivepotential-to initiatea discharge in tubezRAl betw-een the start "anode334- andth =cathodei333', which is-c-onnected'to negative'bab tery.Sincethe-main anode of tube RAI isgconnected' to positive batterythrough the-winding of relay-RA, tube RAI will undergo an immediatetransfer of discharge whereby the conductivepath. will exist across:themain gapoftube RAI .and relay EA will be operated.

Relay RA, in operating, connects negativebat tery through its No. 3contact toconductor 340 which extends to the operating windingsofall ofthe-register 'and'steering relays DR-l to DB0. The other terminal ofeach of the operating windings ofthese relays is connected to one'of thetube output conductors; such as conductors. 3'22, 34! or 342. Under thiscondition, if the initial digit received corresponds to the initial?digit of the designation of the subscribers station with which thesubject apparatus is associated, relay DRI will'be operated. Thus, assuming that the digit "8 has been received, terminal 323 will have risen toa potential positive -relative to the'negative' battery connected to theleft-hand terminal of relay DRI and, as a result, relay DRI will beoperated. It'willbe seen that had the initial digit been any other=digitthan 8, the conductive path in tube Tl would not have included A cathodeIA8, terminal 323" would: not havebeenatj an elevated potential.

at the commencement of the interdigital delay period and relay DRI wouldnot have been operated.

Relay DRl locks operated over a path from negative battery, lockingwinding and No. l contact of relay DRI, conductor 343, and to groundthrough the No. I contact of relay ON. Relay DRI, in operating opens itsNo. 3 contact to disconnect the pulse-generator transformer 309 from theB" cathodes of tube TI and closes its No. 2 contact to connect thatpulse source to the B cathodes of the next succeeding counting tube T2.

Relay RA, in operating, also completes a circuit from positive battery,No. 2 contact of relay ON, No. I contact of relay RA, resistors 344 and345 and via conductor 3) to the start anodes ISA to USA of all of thestepping tubes TI to T0. The application of this positive potential tothe start anode ISA of tube Tl causes the conductive path in tube TI totransfer so as to exist momentarily between the start anode ISA and thestart cathode ISC. The discharge will then transfer so as to existbetween the main anode MAI and the start cathode ISC of tube TI. Thus,tube Tl may be restored to its initial condition in this manner ifdesired. The network comprising resistors 344 and 346 and capacitor 341provides a time delay to ensure that tube Tl will not be restored tonormal before relay DR! has had time to operate and lock operated.

When relay RA operates, negative battery is connected through the No. 3'contact of relay ON, No. 4 cont-act of operated relay L, and through theNo. 2 contact of relay RA to the winding of relay RA and to the mainanode of tube RAI whereby relay RA is locked operated under the controlof relay L and tube RAI is extinguished.

At the first pulse representing the second digit of the receiveddesignation, relay L momentarily releases thereby releasing relay RA sothat negative battery is no longer connected to the operating windingsof the DR-series of relays. At the termination of this pulse, relay Lreoperates and transformer 309 transmits a negative pulse through thefront contacts of operated relay SR, conductor 315, No. 4 contact ofrelay DRO, No. 3 contact of relay DR2, No. 2 contact of operated relayDRI and to ground through resistor 349 whereby a negative pulse isapplied to the B cathodes 23! to 230 of the second digit counting tubeT2. Tube T2 is stepped in a manner similar to the operation of tube TIand, at the next interdigital pause, relay DRZ is operated if, but

only if, the second-received digit corresponds to the second digit ofthe designation of the subscribers station with which the apparatus isassociated, herein assumed to be the digit 5.

The apparatus continues to operate in this fashion, with the succeedingDR-series relays being operated if the successive received digitscorrespond, respectively, with the successive digits of the subjectsubscribers designation. As each DR relay except the last operates, itlooks operated and transfers the pulse lead to the next succeedingstepping tube.

If the received designation does correspond to the designation of thesubscribers station the register and steering relays DR! to DB0 will besuccessively operated; otherwise, at least relay DRO will remainunoperated. Upon the operation of relay DRt, signifying that the subjectsubscriber should be signaled, the visual signal comprising lamp VS andthe audible signal com- 8 prising bell AS Will both be operated overpaths from battery through the contacts of operated relay DRO to groundthrough the No. I contact of relay ON.

When the called subscriber lifts the handset HS, the No. I switchhookcontact will be closed to connect the handset HS to the receiver RE andthe No. 3 switchhook contact will be opened to release relay ON. On theother hand, if the incoming pulses do not designate the particularstation shown in Fig. 3, relay ON will be released when the receiver REremoves the ground from conductor 302. In either case, relay ON, inreleasing, restores the apparatus to normal, extinguishing all of thedischarged tubes, releasing the operated relays, and deenergizing theaudible and visual signals if they have been energized.

It is to be understood that the above-described arrangements are butillustrative of the application of the principles of the invention.Numerous other arrangements may be devised by those skilled in the artWithout departing from the spirit and scope of the invention.

What is claimed is:

1. In a signaling system, a plurality of gaseous conduction devices eachhaving a plurality of distinct conduction positions and each responsiveto electrical impulses applied thereto to advance the conductive paththerein step by step from position to position, an impulse generatoroperable to transmit a series of groups of electrical impulses, a chainof relays comprising a relay individual to each of said devices, meansin cluding contacts on each of said relays for normally electricallyconnecting said impulse generator to the first one of said devices,means for operating each of said relays only if the conductive path inthe one of said devices to which each of said relays is individual isstepped to a preselected position, each of said relays except the lastone of said relays being operable to transfer the connection of saidimpulse generator to the next succeeding one of said devices, signalmeans, and means responsive to the operation of the last one of saidrelays for operating said signal means.

2. In a signaling system, a plurality ofgaseous conduction devices eachhaving an anode, a first plurality of cathodes and a second plurality ofcathodes, each of said devices being responsive to pulses applied tosaid second plurality of cathodes therein to advance the conductive paththerethrough step by step so that said path exists between said anodeand successive ones of said first plurality of cathodes, an impulsegenerator operable to transmit a series of groups of electricalimpulses, means normally electrically connecting said impulse generatorto said second plurality of cathodes in said first device, and apparatusincluding said means connected to a preselected one of said firstplurality of cathodes in each of said devices and operative only inresponse to the advancement of the conductive paths to include therespective preselected ones of said first plurality of cathodes in thesuccessive ones of said devices for successively electrically connectingsaid impulse generator to the said second plurality of cathodes in thesuccessive ones of said devices.

3. In a signaling system, a plurality of gaseous conduction devices eachhaving an anode, a first plurality of cathodes and a second plurality ofcathodes, each of said devices being responsive to pulses applied tosaid second plurality of cathodes,therein., .tc advance theconductivepath here hrough. st p. y stepso that said path, ex.- ists between saidanode and successiv on s of said first plurality of cathodes, an impulsegeneratoroperableto transmit a series of groups of electrical impulses,means normally electrically connecting said impulse generator to saidsecond plurality of cathodes in said first device, appae ratus includingsaid means connected to apreselected one of said first plurality ofcathodes in each of said devices except the last one of said devices andoperative only in response to the ad an emen of in? q duQ l i? Path o.clude the respective preselected .ones of said first plurality ofcathodes in the successive ones of said devices for successivelyelectrically connecting said impulse generatorto the said secondplurality of cathodes in the successive onesof said devices, .signalmeans, and means responsive to the advancement of the. conductive pathin the last one of said devices .to include the preselected one ofthesaid first plurality of cathodes in said last device for operatingsaid signal means.

4. In a signaling system, a plurality of gaseous conduction .deviceseach having ,an anode, .afirst plurality of cathodes and a secondplurality of therein to advance the conductive path therethrough step bystep so that said path exists between said anode and successive ones ofsaid first plurality of cathodes, an impulse generator operable totransmit a series of groups of electrical impulses, means normallyelectrically connecting said impulse generator to said second pluralityof cathodes in said first device, apparatus connected to a preselectedone of said first plurality of cathodes in each of said devices forsuccessively electrically connecting said impulse generator to the saidsecond plurality of cathodes in the successive ones of said devices, andmeans operable at the termination of each of said groups of pulses foroperating said apparatus only if the conductive paths in the successiveones of said devices have been advanced to include the respectivepreselected ones of said first plurality of cathodes in the successiveones of said devices.

5. In a signaling system, a plurality of gaseous conduction devices eachhaving an anode, a first plurality of cathodes and a second plurality ofcathodes, each of said devices being responsive to pulses applied tosaid second plurality of cathodes therein to advance the conductive paththerethrough step by step so that said path exists between said anodeand successive ones of said first plurality of cathodes, an impulsegenerator operable to transmit a series of groups of electricalimpulses, means normally electrically connecting said impulse generatorto said second plurality of cathodes in said first device, apparatusconnected to a preselected one of said first plurality of cathodes ineach of said devices for successively electrically connecting saidimpulse generator to the said second plurality of cathodes in thesuccessive ones of said devices, means operable at the termination ofeach of said groups of pulses for operating said apparatus only if theconductive paths in the successive ones of said devices have beenadvanced to include the respective preselected ones of said firstplurality of cathodes in the successive ones of said devices, signalmeans, and means responsive only to the advancement of the conductivepath in the last one of said devices to include the preselected one ofthe said first plurality of cathodes in said last.- device. for.operating said signal means. I

6. In a signaling system, a plurality of. gaseous conduction devices'each having an anode, a first plurality of cathodes and a secondplurality of cathodes, each of said devices beingrespons'ive to pulsesappliedto said second plurality of cathodes therein to advance theconductive path therethrough step .by step so that said path exists.between said anode andsuccessiveones of said first plurality ofcathodes, an imp'ulsegenerator operable to transmit a series of groupsof electrical impulses, and a chain of relayscomprising a relayconnected .to apreselected o'neiof the said-first plurality of cathodes.in each of 'saiddevic'es and operative only .inrespons'e' tothe'advancem'ent 'of the conductive path to include the said preselectedcathode in'lthe associated one of said devices .forielectricallyconnecting said impulse generator to the next succeeding one of" saiddevices. 1

7. Ina signaling system, aplurality of gaseous conduction .devicesieachhaving .an anode, afirst plurality of cathodes and asecond plurality .01cathodes, each of said, devices lbeinglresponsive. to pulsesappliedto,saidsecondplurality. ofcathodes therein to advance theconductive .path there through stepbystepso that said path existsbetween said anode and successive ones of said first plurality ofcathodes, an impulse generator operable to transmit a series of groupsof electrical impulses, and a chain of relays normally electricallyconnecting said impulse generator to said second plurality of cathodesin said first device and comprising a relay connected to a preselectedone of the said first plurality of cathodes in each of said devices andoperative only in response to the advancement of the conductive path toinclude the said preselected cathode in the associated one of saiddevices for electrically connecting said impulse generator to the nextsucceeding one of said devices.

8. In a signaling system, a plurality of gaseous conduction devices eachhaving an anode, a first plurality of cathodes and a second plurality ofcathodes, each of said devices being responsive to pulses applied tosaid second plurality of cathodes therein to advance the conductive paththerethrough step by step so that said path exists between said anodeand successive ones of said first plurality of cathodes, an impulsegenerator operable to transmit a series of groups of electricalimpulses, a chain of relays normally electrically connecting saidimpulse generator to said second plurality of cathodes in said firstdevice and comprising a relay connected to a preselected one of the saidfirst plurality of cathodes in each of said devices and operative onlyin response to the advancement of the conductive path to include thesaid preselected cathode in the associated one of said devices forelectrically connecting said impulse generator to the next succeedingone of said devices, and signal means operative in response to theoperation of the one of said relays associated with the last one of saiddevices.

9. In a signaling system, a plurality of gaseous conduction devices eachhaving an anode, a first plurality of cathodes and a second plurality ofcathodes, each of said devices being responsive to pulses applied tosaid second plurality of cathodes therein to advance the conductive paththerethrough step by step so that said path exists between said anodeand successive ones of said first plurality of cathodes, an impulsegenerator operable to transmit a series of groups of electricalimpulses, a chain of relays normally electrically connecting saidimpulse generator to said second plurality of cathodes in said firstdevice and comprising a relay connected to a preselected one of the saidfirst plurality of cathodes in each of said devices, and apparatusoperable at the termination of each of said groups of pulses forsuccessively operating said relays only if the conductive paths in thesuccessive ones of said devices have been advanced to include thepreselected ones of said first plurality of cathodes in the successiveones of said devices.

10. In a signaling system, a plurality of gaseous conduction deviceseach having an anode, a first plurality of cathodes and a secondplurality of cathodes, each of said devices being responsive to pulsesapplied to said second plurality of cathodes therein to advance theconductive path therethrough step by step so that said path existsbetween said anode and successive ones of said first plurality ofcathodes, an impulse generator operable to transmit a series of groupsof electrical impulses, a chain of relays normally electricallyconnecting said impulse generator to said second plurality of cathodesin said first device and comprising a relay connected to a preselectedone of the said first plurality of cathodes in each of said devices,apparatus operable at the termination of each of said groups of pulsesfor successively operating said relays only if the conductive paths inthe successive ones of said devices have been advanced to include thepreselected ones of said first plurality of cathodes in the successiveones of said devices, and signal means operative in response to theoperation of the one of said relays associated with the last one of saiddevices.

EDWARD VROOM.

REFERENCES CITED The following references are of record in the file ofthis patent:

